In general, hydrogenated nitrile rubber is produced by the hydrogenation of the carbon-carbon double bonds contained in nitrile rubber. Vulcanizates of hydrogenated nitrile rubber are known to have excellent resistance to heat, oil and ozone.
Plasticizers are sometimes used in hydrogenated nitrile rubber to modify the processing characteristics or to improve the low temperature properties of the vulcanizates. However, it is generally acknowledged that the use of plasticizer in hydrogenated nitrile rubber compositions produces an undesirable side effect, namely a reduction in resistance to hot air ageing. Thus conventionally, heat resistant plasticizers with low volatility such as low molecular weight trimellitate compounds are generally preferred in order to minimize the impairment of resistance to hot air ageing.
Heretofore, there has not been provided a plasticized, hydrogenated nitrile rubber composition having improved low temperature properties and improved resistance to hot air ageing, and it is an object of this invention to provide such a composition.